It is known to dry grain to enhance its storage characteristics. In a typical grain drying apparatus, oil or coal is burned to provide hot gases which are circulated throughout the grain to dry it. Such a process is expensive because of the high prices for coal or oil. U.S. Pat. No. 3,562,921 (Lindl) shows a grain dehydrator wherein an oil or gas furnace produces hot gases for drying the grain. A cyclone-type separator separates the dried grain from gaseous odors, which are then reburned for supplementing the hot gases from the furnace. The burning of agricultural waste products to produce heat is also known. U.S. Pat. No. 4,398,477 (Iwasaki) shows an apparatus for directing combustible material, such as the hulls of rice, to a furnace to produce a swirling flow of combustible products.
A fluidized bed is also known for combustion processes. U.S. Pat. Nos. 4,469,050 (Korenberg) and 4,378,744 (DeFeo et al.) show fluidized bed reactors for burning material. In each of these devices, the desired output heat is obtained by a heat exchanger in contact with the fluidized bed.
Cyclones are also known for use in separating gases from solid materials. U.S. Pat. No. 3,477,650 (Williams) shows such a device, as do the Korenberg, DeFeo et al. and Lindl patents.